Contact lenses are made by curing a liquid monomer in a mold and thereafter breaking the mold to remove the hardened lens, or by machining the lens out of a plastic block. When a color is imparted to the lens, the lens can alter the color of the eyes to which they are applied. The ink which imparts the color can irritate the eye and, therefore, it is desirable to color the outer surface of the lens and not the inner surface. One method of applying color to a contact lens is to deposit a coating of ink on the portion of the mold which forms the convex surface of the lens before the liquid monomer is inserted. As the liquid monomer hardens, it bonds with the ink thereby imparting color to the lens.
If the coloring is not to be applied to the contact lens within the mold, it must be applied after the lens has been manufactured. It has been found that when a mold is broken to remove a molded lens that the lens tends to remain in the concave side of the mold leaving exposed the concave side of the lens. Since it is desirable to apply the ink to the convex surface, the lens must be entirely removed from the mold before the coloring is applied. A method has been developed whereby the concave surface of the mold can be treated with a substance which changes the surface energy of the convex side of the lens such that when a treated mold is broken to remove the lens, the concave portion of the lens will be retained in the convex portion of the mold leaving the convex surface of the lens exposed. The portion of the mold retaining the lens can, therefore, be used to handle the lens during the coloring process.
There presently is no suitable method for handling a contact lens for applying a color thereto where the lens is machine manufactured on a mandrel or the lens is molded and the technologies of coloring within the mold, or changing the surface energy of the convex surface are not available. It is the intent of the present invention to provide a method and apparatus whereby such a contact lens can be retrained for applying color thereto without employing either of the above described technologies.